Dioxins

In Article <MPG.10914a47a15d6f35989a65 at news.teleport.com>,
larryc at teleport.com (Larry Caldwell) wrote:
>>The chemicals (Orange was a mix) themselves were safe enough. It was the
>trace contaminants that proved to be the problem.
What exactly is the problem? "There is no evidence that dioxin causes any
serious health effects in humans apart from chloracne and some reversible
liver dysfunctions". (M.Gough, Sci. Total Environ. v.104 p.129, 1991).
"Everyone carries a certain body burden of dioxins and furans; it has been
found that only the 2,3,7,8-substituted compounds accumulate, with levels of
the higher chlorinated homologues predominating." (Dioxins in Food, UK
Ministry of Agriculture, Fisheries and Food, Food Surveillance Paper No. 31.
p.9, 1992, ISBN 0 11 242926 2).
>From an environmental standpoint, dioxin contaminants are caused by
>industrial processes.
Don't forget forest fires and other natural sources.
"In previous reviews in the UK and Sweden, the 'known' sources of dioxins
(manufacture of chlorinated organic compounds, chlorinated waste
incineration, wood and coal burning, metal recycling and wood-pulp and paper
bleaching) account for only 10% of depositions. The EPA review draws similar
conclusions for the US, but these estimates are based on relatively few
observations." (Dioxins released from chemical Accidents, A.A.Meharg,
D.Osborn, Nature v.375 p.353-354, 1995).
>Emission controls on gaseous and liquid effluents
>have sharply limited the amount of dioxins being released into the
Furthermore, dioxin levels in US human adipose tissue have been decreasing
since about 1970, from around 18 pg/g lipid in 1971 down to around 4 pg/g
lipid in 1987. (PCDD and PCDFs concentration levels in human adipose tissue
samples from the continental US collected from 1971 through 1987,
J.S.Stanley et al., Chemosphere v.20 p.895-901, 1990.)
Tracy